Undercutter



Feb. 13, 1951 G. w. NEwcoMB UNDERCUTTER 2 Sheets-Sheet l Filed July 22,1946 INVENTQR.

ATTDRNEYS Feb, 13 1951 G. w. NEwcoMB 2,541,537

UNDERCUTTER Filed July 22, 1946 2 Sheets-Sheet 2 QJ /I l "6 J @a J3711.9 g3 J? .9/ i T-. J3 J6 5 2? I les' 1 j .93 Zoy? V Il'f/ lm W f INVEN TOR.

ATTE] RN EYE Patented Feb. 13, 1951 UNITED sTATEs lPATENT OFFICEUNDERCUTTER George W. Newcomb, Baltimore, Md. Application July 22, 1946,Serial No. 685,444

2 Claims. 1

This invention relates to a socket cutter, and it is one object of theinvention to provide a cutter by means of which sockets may be .formedin furniture and the like to receive ends of dowel pins, chair rounds,bars, and the like, the socket being so cut that it increases indiameter towards its inner end, and thus allows the end of a dowel pindriven into the socket to be spread by a wedge deposited in the socketand firmly held against dislodgement from the socket,

Another object of the invention is to provide an under-reamer withcutters which are nor* mally in a retracted position allowing theunderreamer to cut its way into the wallfof a previously bored hole in achair leg or the like and form a socket, means being provided forguiding the cutters outwardly and enlarging the socket after the holehas been cut to a predetermined depth.

Another object of the invention is to provide an under-reamer withcutters which rare slidable longitudinally of the under-reamer ingrooves formed therein, lower portions of the grooves having slopingsurfaces acting as cams for guid-y ing the cutters outwardly when thecutters are forced downwardly.V Another object of the invention is toprovide actuating means for expelling the cutters consistingof a collarloosely mounted about the under-reamer, and yieldably held in a raisedposition by a spring which maintains the collar in contact with cams ofa lever pivoted to a second collar. It will thus be seen that after asocket has been started, the lever may be swung downwardly, and the camswill apply pressure to force the cutters outwardly. n

Another object of the invention is to provide an under-reamer havingsocket enlarging means associated with it, which is o'f simplevconstruction and easy to operate.

The invention is illustrated in the accompanying drawings wherein:

Figure 1 is a side view of the improved drill with the auxiliary cuttersin a retracted position;

Figure 2 is a side View showing 'the auxiliary cutters extended to forma socket gradually increased in diameter toward the inner end;

Figure 3 is a fragmentary view showing a cam of modified formation;

Figure 4 is a view looking at the lower end of the under-reamer with theauxiliary cutters retracted;

Figure 5 is a view similar to Figure 4 showing the auxiliary cuttersextended;

Figure 6 is a view showing the under-reamer in longitudinal section withthe auxiliary cutters retracted;

Figure 7 is a view similar to Figure 6 showing the auxiliary cuttersextended;

Figure 8 is a sectional view 8 8 of Figure '7;' t

Figure 9 is a sectional view takenalong line 8-9 of Figure 6;

Figure 10 is a sectional View taken along line lG-Iof Figure 6;

Figure l1 is a side View of an end a dowel;

Figure 12 is an end view of the dowel;

Figure 13 is a Viewl showing the dowel fitted into a socket and itsinserted end expanded; f

Figure 14 is a view taken along line Ill-I4 of Figure 13;

Figure 15 is a view of a wedge by means of which the dowel pin isspread.

The improved under-reamer constituting the subject matter of thisinvention is used for cutting sockets to receive dowel pins, chairrounds, or the like. When a drill of conventional con, struction isused, a socket yis formed which is of an even diameter throughout itsdepth, and even if a Wedge is placed in the socket to spread the end ofa dowel pin or round, a permanent mounting will not be obtained, as thedowel' pin may work loose and slip out of the socket.

The under-reamer l may be of any desired length and diameter, and whenin use is mounted in a drill chuck 2. The lower end of the underreamermay be formed with cutting teeth or the under-reamer sharpenedin anymanner desired so that when the underi-reamer is turned in a previouslybored hole A, a socket 3 will be formed in a board, chair leg, orthelike 4. Groovesf extend longitudinally of the under-reamer and each hasits lower 'endg portion gradually; decreased in depth to forma camsurface 6 extend'- ng downwardly at anoutward incline as shown inFigures 6 and 7. Auxiliary cutters 9 are slidably mounted in the groovesor recesses 5, and

taken along line portion .of

each cutter has its lower portion -9 extending`y downwardly at anoutward incline and its upper end formed with an outwardly extendinglinger Il. The fingers ll engage in sockets I2 formed in a collar I3which ts'loosely about the underreamer and is slidable along theunder-reamer from the raised position shown in Figure 6 to the loweredor depressed )position shown in Figure "l, A sec-ond collar ,I4 ts aboutthe under-reamer, where it is secured in predetermined spaced relationto the lower end thereof, and upon this `which has its upper end bearingagainst the under surface of the collar I3 so that the collar I3 will beurged upwardly to the raised position. Spaced upwardly from collar I 3is a ring or collar I8 secured by a pin I1 which passes transverselythrough the under-reamer, and between the ring I6 and the collar I3 is asleeve I8. The sleeve I8 is free upon the under-reamer, and carries pinsI9 which pass through the forks for arms 20 of a lever 2I and pivotallymount 'the lever. Cams 22 project from the arms of the lever or handle2I and the curved lower edge faces of the cams bear against the uppersurface of a wear ring or disk 23 which rests upon the collar I3. Whenthe handle is swung downwardly, the collar I3 will be moved downwardlywith it, and as the collar moves downwardly, 'the cutters 3 will ,beshifted downwardly in the grooves and their lower ends'gradually shiftedoutwardly bythe cam surfaces 6. Therefore, aft-er a socket has been cutto a desired depth, the auxiliary cutters may be gradually movedoutwardly anda. socket will be formed of gradually increasing diametertoward its inner end. A dowel pin or chair round 24 formed with crossedslits 25 leading from its end will be driven into a socket after across-shaped wedge 26 has been deposited rin the socket, and as the armsof the wedge enter the slits `25, the dowel pin or round will be spreadand firmly anchored in the tapered socket as shown in Eigure 13.lInstead of providing arms of the handle 2'I with cams 22, cams 21 of'substantially elliptical or oval shape may be mounted upon end`portions of the ipins I9 inwardly of the arms of the lever or xedlysecured to the "lever arms to turn therewith. Such cam plates 'arewshown in Figure 3, and referring to this Figure, it will be seen thatbearing balls 24 may be provided between the disk 23 and the collar I3,land thus form a bearing for the collar. A similar bearing is providedabove the cam plates and consists of a disk 25 and 'bearing balls 25.With an under-reamer of the improvedr construction, vsockets may bequickly cut and be either of an e'vendiameter or tapered toward theirouter ends so that dowel pins driven into the sockets will 'be wedged invthe sockets 'and very rmly held against displacement from 'the sockets.

Having thus described the invention, what is claimed is:

1. `An under-reamer comprising a substantial- Iy cylindrical shankformed with longitudinally extending grooves spaced from each other lcircumferen-tially of the shank, and having their lower end portionsgradually decreased in depth to provide cam surfaces extendingdownwardly 'at an outward incline, cutters having vcutting edgesslidable longitudinally in said grooves and having their lower portionsextending at an outward incline, fingers extending from upper ends ofsaid: cutters and projecting radially from the shank, a collar looseabout said shank and formed with sockets into which the fingers 'fit toconnect the cutters with the collar, a second collar secured about thelower end 'portion of the shank adjacent to the upper edge of the camsurface of the grooves and engaging the edge surface of the cutterswhereby to cam them inwardly as they are moved upwardly on the shank, ahelical spring surrounding the shank between the collars and urging therst collar upwardly to a raised position for holding the cutters re--tracted, a ring secured about said shank above the first collar, asleeve fitting loosely about the shank between the rst collar and saidring, pins projecting from opposite 'sides of vsaid sleeve, a leverhaving arms at its lower end pivoted upon said pins, and cam membersextending from said arms and having curved lower edges engaging the .rstcollar for forcing the same downwardly and cause the cutters to beshifted downwardly in the grooves and gradually moved outwardly to anextended position by engagement with the cam surfaces at lower ends ofthe grooves and the depth vof the grooves being so that the cutters willnot project beyond the shank in their uppermost position but willproject beyond theshank in 'their lowermost cutting position.

2. An under-reamer comprising a substantially cylindrical shank formedwith longitudinally extending grooves, having lower portions providedwith outwardly sloping cam surfaces, cutters having cutting edgesslidable longitudinally in said grooves and having lower end portionsextending outwardly at an incline, and moved to an extended position byAengagement with the cam surfaces when the cutters are shifteddownwardly in the grooves, and the depth. of the grooves being so thatthe `cutters will not project beyond the Ashank in their up-A per-mostvposition vbut will project beyond the shank in their lowermost.position an abutment about the lower portion of said shank adjacent tothe upper edge of the cam surfaces of cthe grooves and engaging the edgesurface of the' cutters whereby to cam them inwardly as they are movedupwardly on the shank, a collar loose about the shank above theabutment, a spring about the shank between the abutment and the collarand urging the collar upwardly, said cut ters having their upper endsconnected with the collar and being` held in a retracted position whenthe collar is in its raised position, a ring secured -about the shankabove the collar, a sleeve about the shank between the collar and thevring, and a lever having arms pivoted to op-l posite sides of the sleeveand provided with 'cams acting upon the collar to force the collardown-z wardly and Vshift the cutters to an extended position when thelever is swung downwardly.

GEORGE W. NEWCOMB.-

REFERENCES CITED The following references are of record in ther iileVof. this patent:

Huelster May 28, 1946

